Blower



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United States Patent 3,193,265 BLQWER .lames A. ewan, lliarengo, Illassignor to Chicago Eastern Qorporation, hlarengo, llL, a corporation ofIllinois Filed Sept. 39, 1964, Ser. No. 499,424 h Claims. (\Cl. 263-19)This invention relates in general to heating systems. It deals moreparticularly with a system for heating and circulating substantialquantities of air.

It is, of course, a well-known expedient to use a forced air heatingsystem for agricultural crop drying and the like. Such a systemconventionally combines a motor driven blower fan and a gas burnersuitably disposed in a housing so that the blower fan drives air througha combustion area where it is heated by burning gas and then directedinto a crop drying enclosure. The present invention is specificallyconcerned with eflicient heating of the driven air by the gas burner.

it is an object of the present invention to provide an improved forcedair heating system which assures more efiicient combustion of the gases.

It is another object to provi e a forced air heating system whichprevents undesirable recirculation of unburned gases.

it is still another object to provide a system wherein the formation ofcarbon monoxide is avoided.

It is yet another object to provide a simple and inexpensive burncrassembly which forest-ails recirculation of unburned gases.

It is yet a further object to provide a burner assembly which controlsair flow to achieve more complete combustion and avoid carbon monoxideformation.

The foregoing and other objects are realized in accord with the presentinvention by providing a forced air heating system including a burnerassembly which controls the how of air through the combustion area ofthe system so that recirculation of unburned gases is avoided. Air howis controlled such that more complete combustion is achieved and optimumheating of the air is alforded while the formation of highly undesirablecarbon monoxide is avoided.

The invention, both as to its organization and method of operation,taken with further objects and advantages thereof, will best beunderstood by reference to the following description taken in connectionwith the accompanying drawings, in which:

FIGURE 1 is a perspective view of a forced air heating unit embodyingfeatures of the present invention;

FIGURE 2 is an enlarged rear end elevational view of the heating unitillustrated in FTGURE 1;

FIGURE 3 is a sectional View taken along line 3-3 of FIGURE 2, withparts removed; and

FIGURE 4 is a sectional view similar to FTGURE 3 illustrating a burnerunit embodying features of a modilied form of the present invention.

Referring now to the drawings, and particularly to FIGURES 1-3, a forcedair heating unit embodying features of the present invention isillustrated generally at The unit it} includes a generally cylindricalhousing 11 formed of sheet steel or the like through which air is drivenby a blower assembly 15 mounted within the housing 11. The blowerassembly i forces air past a burner assembly 16 which burns a separatemixture of natural or manufactured gas and air in the forced air streamand thereby heats the forced air before it leaves the unit it). Suitableconduiting (not shown) normally is provided for directing the heated airto a crop drying enclosure or the like.

The blower assembly draws airs into the tip-stream EJ932555 PatentedJuly 6, 1965 inlet 2%. of the housing 11 through a guard screen 21mounted thereon and drives the air past the burner assembly 16 out ofthe down-stream outlet 22. The downstream outlet 22 is normallyconnected to the conduiting (not shown) hereinbefore referred to anddesigned to connect the unit 16 to a corn drying bin, for example.

The blower assembly includes an electric motor 25 mounted concentricallywithin the housing 11 between a series of radially extending statorblades 26. The stator blades are preferably fabricated of sheet steeland are secured at their outermost ends 27 to the inner surface of thehousing 11 by conventional bolt assemblies (not shown). At theirinnermost ends 2-8, the stator blades 26 are secured to a generallycylindrical casing which supports the motor 25 within its confines onradially disposed brackets 36. The motor 25' is actuated and controlledfrom a conventional control box 37 mounted on the outside of the housing11 through a shielded conduit 38 in a well known manner.

The drive shaft 40 of the motor 25 protrudes from its body 41 toward theinlet 2% of the housing 11 and mounts a blower fan 42 for rotation aboutthe longitudinal axis of the housing ll. The blower fan 42 includes acylindrical rotor 43 and a mounting spider 44 secured thereto byconventional bolt assemblies 45. The spider 54- is a casting whichincludes a sleeve slipped over the shaft 4 and secured thereto by setscrew means (not shown).

Radiating from the cylindrical rotor 43 and secured thereto by weldingor the like are a plurality of rotor blades 5%. The rotor blades 5t areof broadly conventional construction and, when rotated with the rotor 43on the drive shaft 4t, serve to draw air in the inlet end 20 of thehousing 11 through the screen 21 and drive it past the stator blades 2-3hereinbefore described. The stator blades 25 are angulated incross-section, as seen in FIGURE 3, and thus serve to straighten out therotational flow of driven air and direct it axially past the burnerassembly 16 with a reduced rotational component.

The burner assembly 16 includes a burner ring 55 which might befabricated of pipe 56 or the like, and formed into What approximates acircle about the longitudinal axis of the housing 11, as illustrated. Inthe alternative, the ring 55 can also be cast in shape, of course, as itpreferably is in practice. The pipe 56 is capped at its free end 57 andconnected at its opposite end 58 to a gas inlet fitting 59 inserted inthe open end 5% of the pipe adjacent a short straightened section 60thereof.

The inlet fitting 5h is solidly mounted in the housing ill by anysuitable mounting arrangement and extends through the housing into a gasinlet regulator unit secured to the outside of the housing. The inletfitting 59 supports the burner ring 55 as well as conducting natural ormanufactured gas from the regulator unit 65 into the pipe $6. The gas,which in practice is usually propane, is metered through the unit 65 ina controlled manner, as by control valve es, from a source (not shown)secured to the nipple 67.

The propane is mixed in the pipe 56 at a prescribed ratio with airadmitted thereto in a well known manner from orifice means (not shown)in the upstream face 7% of the pipe. This combustible mixture of propaneand air is then emitted from the pipe 56 through a series of closelyspaced burner apertures '71 formed in the downstream face 72 of the pipe55. The apertures '71 are all formed within the confines of a flameretainer sub-assembly 73 secured to the downstream face 72..

The flame retainer sub-assembly '73 comprises air impervious inner andouter flame retainer walls 77 formed of strip steel or the like weldedto the downstream face 72 of the pipe 56 in bracketing relationship withthe apertures 71. The walls 7'7 terminate in free edges 78 downstream ofthe apertures 71. End sections 79 of the sub-assembly 73 interconnectthe walls 77 at their opposite ends to complete a flame retainer well 80shielding the apertures 71 and permitting a combustible mixtureof gasand air to accumulate and ignite after being emitted from the apertureswithout first being dissipated y the blast of air driven past the pipe56 from the blower fan 42.

The combustible gas-air mixture is ignited by a conventional sparkignition system as it leaves the mouth 81 of the well 80. The ignitionsystem, which includes a conventional control and transformer box 82mounted on the housing 11, provides a continuing spark at the mouth 81through are forming elements (not shown) in a well-known manner.

past the pipe 56 and the heated air is delivered to the aforementionedcrop drying enclosure.

To avoid the recirculation of unburned gas, and to Supply sufiicientsecondary air to the ignited gas so that complete combustion is achievedand the formation of carbon monoxide, for example, is avoided, theburner assembly 16 incorporates an air shroud sub-assembly 85constructed and arranged according to the present invention. The airshroud sub-assembly 85 channels and directs a portion of the air drivenpast the burner assembly 16 transversely across the mouth 81 of theflame retainer well 80.

The converging flow of air across the downstream edges 78 of the walls77 serves to obviate the suction cifect of negative pressure areascaused by the motor body 41, or the burner ring 55 or the like, andprevent: recirculation of unburned gases upstream. Atthe same time, thisair flow pattern supplies additional secondary air to the gas ignitedimmediately downstream of the V The flame propagated at the mouth 81 ofthe flame retainer well 80 heats air driven well mouth 81 and assuressubstantially complete comis secured to the housing 11 by radialbrackets 90 and conventional bolt assemblies (not shown).

, The deflector rim 86 comprises an upstream rim section 93 whichextends substantially parallel to the axis of the housing 11 and aconverging downstream rim section 94 which terminates at a rim edge 5axially aligned with thetdownstream edges 78 on the flame retainer walls77. The outer deflector rim forces a portion of the air driven past theburner ring laterally across the mouth 81 of the flame retainer well 80.

Opposite the outer deflector rim 86 in bracketing relationship with theburner ring 55 is an annular air inpervious inner deflector rim 100. Theinner deflector rim 190 comprises an upstream rim section 105 extendingsubstantially parallel with the axis of the housing 11 and a divergingdownstream section 106 which terminates at a rim edge 107 which lies ina plane approximately axially aligned with the plane in which edges 78on the flame retainer walls 77 lie.

It will now be seen that driven air immediately adjacent the annularcasing 28 surrounding the motor 25 passes outside the inner deflectorrim 100-and is directed outwardly over the mouth 81 of the flameretainer well 80. At the same time the outer rim 86 directs air inwardlyimmediately over the mouth 81 of the flame retainer well 80.Accordingly, the circulation or eddy current flow of those as yetunburned gases backwardly along the outside of the flame retainer walls77 is eliminated. Furthermore, 'sufiicient secondary air is introducedto the combustion area immediately downstream of the well mouth 81 toachieve complete combustion and the formation of carbon monoxide, forexample, is avoided.

The invention has thus far been described only in the context of aforced air heating unit 10 wherein the fan 4-2 is arranged to firstdrive air past the driving motor 25 and then the burnertassembly 16.FIGURE 4, however, illustrates a unit ltla wherein the blower fan 42a ismounted downstream of the motor 251;. In such case, the rotation ofblower fan 42a creates a negative pressure area adjacent to the front ofthe cylindrical rot-or 43a which in turn tends to cause a reverse airfiow pattern through the center of the inner rim ltltla. To preventforced air which has already been heated from recirculating through theinside of the inner rim 109a upstream to overheat the blower fan 42a, aslightly modified air shroud sub-assembly a is employed. To this end, acircular closure plate 12% is connected to the downstream edges 107a ofthe diverging rim sections Idea on the innerdeflector rim a. In allother respects, the forced air heating unit 10a is substantiallyidentical to that hereinbefore described, and illustrated in FIG- URES1-3. Accordingly, corresponding components are identified bycorresponding reference numerals with the addition of the suffix a.

The forced air heating units It) and 16a hereinbefore described effectextremely eflicient heating of the air driven through housings 11 and11a. Complete combustion is assured with the concomitant avoidance ofany significant carbon monoxide formation. In the case of the unit 10aillustrated in FIGURE 4, recirculation of heated air to overheat theblower fan 42a is also prevented.

It should be recognized, of course, that both units It) and 10a aredescribed somewhat diagrammatically. For example, the housings 11 and110 are frequently twopart assemblies housing the blower assemblies andburner assemblies separately. Furthermore, while embodiments describedherein are at the present considered to be preferred, it is understoodthat various modifications and improvements may be made therein, and itis intended to cover in the appended claims all such modifications andimprovements as fall within the true spirit and scope of the invention.

What is desired to be claimed and secured by Letters Patent of theUnited States is:

1. In a forced air heating system including a housing defining a passageand a blower assembly for forcing air therethrough, the improvementcomprising: a burner ring disposed transversely of the longitudinal axisof said passage and adapted to emit combustible gas through outlet meansformed in a downstream face on said ring, flame retainer walls extendingdownstream of said face in bracketing relationship with said outletmeans to form a flame retainer well, said walls terminating indownstream edges defining a mouth on said well, and air shroud meansbracketing said burner ring, said air shroud means includingsubstantially annular inner deflector means arranged inside said ringand substantially annular outer deflector means arranged outside saidring, said deflector means including converging downstream sectionsadjacent said mouth for directing a portion of the blower driven air'transversely across said mouth immediately downstream thereof to preventrecirculation of unburned gases upstream and supply suflicient secondaryair to assure substantially complete combustion.

2. The improvement in heating system of claim 1 further characterized inthat said converging downstream sections terminate in edges which lie ina plane that is in approximately axial alignment with a plane in whichsaid downstream wall edges lie. V

V 3. In a forced air heating system including a housing defining apassage and a blower assembly mounted in adapted to emit combustible gasthrough outlet means formed in a downstream face on said ring, flameretainer walls extending downstream of said face in bracketingrelationship with said outlet means to form a flame retainer well, saidwalls terminating in downstream edges defining a mouth on said well, andair shroud means bracketing said burner ring, said air shroud meansincluding a substantially annular inner deflector plate arranged insidesaid ring and spaced a predetermined radial distance therefrom, and asubstantially annular outer deflector plate arranged outside said ringand spaced said predetermined radial distance therefrom, said deflectorplates including upstream sections extending generally parallel to eachother and to said axis, and converging downstream sections adjacent saidmouth for directing a portion of the blower driven air transverselyacross said mouth immediately downstream thereof to preventrecirculation of unburned gases upstream and supply suflicient secondaryair to assure substantially complete combustion.

4-. A relatively low pressure forced air heating system for supplyingheated air to an enclosure, comprising: a housing defining a passagehaving inlet means and outlet means, a blower assembly in said passagefor forcing air therethrough from said inlet means to said outlet means,burner means disposed in said passage and adapted to emit combustiblegas through outlet means formed on a downstream face of said burnermeans, flame retainer walls extending downstream of said face inbracketing relationship with said outlet means to form a flame re tainerwell, and air shroud means bracketing said burner means, said air shroudmeans including inner deflector means arranged inside said burner meansand outer deflector means arranged outside said burner means, saiddeflector means including converging downstream sections adjacent saidmouth for directing a portion of the blower driven air transverselyacross said mouth immediately downstream thereof to preventrecirculation of unburned gases upstream and supply sufiicient secondaryair to assure substantially complete combustion.

5. The system of claim 4 further characterized in that said convergingdownstream sections terminate in edges which lie in a plane that isapproximately axial alignment with a plane in which said downstream walledges lie.

6. A forced air heating system, comprising: a housing defining a passagehaving inlet means and outlet means, a blower assembly in said passageincluding a blower fan for forcing air therethrough from said inletmeans to said outlet means, burner means disposed in said passage andadapted to emit combustible gas to outlet means from a downstream faceof said burner means, air shroud means bracketing said burner means,said air shroud means including substantially annular inner reflectormeans arranged inside said ring and substantially annular outerdeflector means arranged outside said ring, said deflector meansincluding converging downstream sections for directing a portion of theblower driven air transversely across said mouth to preventrecirculation of unburned gases upstream and to supply suflicientsecondary air to assure substantially complete combustion, and closuremeans extending between said annular inner deflector means forpreventing the recirculation of heated air upstream to overheat saidblower fan.

7. The system of claim 6 further characterized in that said closuremeans comprises a generally circular plate secured to said annular innerdeflector means around its periphery.

8. A relatively low pressure forced air heating system for supplyingheated air to an enclosure, comprising: a housing defining a passagehaving an inlet and an outlet, a blower assembly in said passage forforcing air therethrough from said inlet to said outlet, a burner ringdisposed in said passage and adapted to emit gas through outlet meansformed on the downstream face of said burner ring, flame retainer Wallsextending downstream of said face in bracketing relationship with saidoutlet means to form a flame retainer well for supporting combustion ofsaid gas, said wall terminating in downstream edges defining a mouth ofsaid well, and air shroud means bracketing said burner ring, said airshroud means including annular inner deflector means arranged insidesaid burner ring and annular outer deflector means arranged outside saidring, said deflector means including converging downstream sectionsimmediately adjacent said mouth for directing the first portion offorced air made available to said combustion transversely across saidmouth immediately downstream thereof to prevent recirculation ofunburned gases upstream and supply suflicient air to assuresubstantially complete combustion.

9. A relatively low pressure forced air heating system for supplyingheated air to an enclosure, comprising: a housing defining a passagehaving an inlet and an outlet, a blower assembly in said passage forforcing air therethrough from said inlet to said outlet, a burner ringdisposed in said passage and adapted to emit gas through outlet meansformed on a downstream face of said burner ring, air impervious flameretainer walls extending downstream of said face in bracketingrelationship with said outlet means to form a flame retainer well forsupporting combustion of said gas, said walls terminating in downstreamedges defining a mouth on said well, and air shroud means bracketingsaid burner ring, said air shroud means including annular innerdeflector means arranged inside said burner means and annular outerdeflector means arranged inside ring, said deflector means including airimpervious upstream sections, and converging air impervious downstreamsections immediately adjacent said mouth for directing the first portionof forced air made available to said combustion transversely across saidmouth immediately thereof to prevent recirculation of unburned gasesupstream and supply sufficient air to assure substantially completecombustion.

References Cited by the Examiner UNITED STATES PATENTS CHARLES SUKALO,Primary Examiner.

4. A RELATIVELY LOW PRESSURE FORCED AIR HEATING SYSTEM FOR SUPPLYINGHEATED AIR TO AN ENCLOSURE, COMPRISING: A HOUSING DEFINING A PASSAGEHAVING INLET MEANS AND OUTLET MEANS, A BLOWER ASSEMBLY IN SAID PASSAGEFOR FORCING AIR THERETHROUGH FROM SAID INLET MEANS TO SAID OUTLET MEANS,BURNER MEANS DISPOSED IN SAID PASSAGE AND ADAPTED TO EMIT COMBUSTABLEGAS THROUGH OUTLET MEANS FORMED ON A DOWNSTREAM FACE OF SAID BURNERMEANS, FLAME RETAINER WALLS EXTENDING DOWNSTREAM OF SAID FACE INBRACKETING RELATIONSHIP WITH SAID OUTLET MEANS TO FORM A FLAME RETAINERWELL, AND AIR SHROUD MEANS TO FORM A FLAME REMEANS, SAID AIR SHROUDMEANS INCLUDING INNER DEFLECTOR MEANS ARRANGED INSIDE SAID BURNER MEANSAND OUTER DEFLECTOR MEANS ARRANGED OUTSIDE SAID BURNER MEANS, SAIDDEFLECTOR MEANS INCLUDING CONVERGING DOWNSTREAM SECTIONS